[steviep187]

Is there a noticable difference between the 3.7L and the 4.0L in the area of torque and power in general? My 3.7L is essentially a turd. It takes some serious planning when it comes to merging into traffic. I love the looks of the Nitro, but it is seriously underpowered.

 

[Nitrogen]

HEMI transplant.

 

[Scar0]

I have a 3.7 and have no issues getting up to speed.
But I also have a CAI, free-flowing exhaust, and a 4.7 Throttle body. To my disadvantage I have a lift and over sized tires...

To get you started however, Disconnect the Neg(-) battery cable for 10 minutes. This will set the computers in "learn" mode.
Then after you reconnect the battery, drive it like you stole it for a while.
Oh and if it has not been done lately change the spark plugs. Do not use Platinum or Iridium plugs in the 3.7! Use only ZFR6F-11G plugs, NGK is OEM brand and what I use. Must be changed every 30K miles.

 

[BearlyNitro]

I've purchased 3 Nitro's so far, the first was a 2007 SLT 4x4 for my wife to replace her Honda CRV, and I liked it so much that I sold my Toyota Sequoia with its V8 engine, and got myself the 2007 Nitro R/T 4x4. So, I have direct experience with both the 3.7L V6 Nitro with an automatic 4 speed transmission, and the 4.0L V6 Nitro with the 5 speed automatic trans. In my opinion, there is a huge difference in performance between the two vehicles, and I would never consider owning the 3.7L V6 Nitro with the 4 speed automatic, unless drastic modifications were done to it. The 3.7L V6 with 4 speed automatic not only performs much worse than the 4.0L V6, but the 3.7L V6 also gets worse gas mileage. I have no experience with the 6 speed manual transmission Nitro's, but think that it would make a big difference, unfortunately, not many manual transmission Nitro's were produced, compared to the automatic transmission models.

I have towed heavy trailers with my R/T Nitro, and it had no problem towing 5,000 lbs or more up steep hills and mountain roads, and only on the steepest grades did my speed dip below 55mph. So, IMHO, yes, there is a significant difference in the performance of the 3.7L V6, when compared to the 4.0L V6 Nitro models.

That being said, it is probably easier to improve the performance of the 3.7L V6, than it is to boost the HP of the already high performance 4.0L V6 in the R/T and later models of the Nitro. So if you already have the 3.7L V6 model of Nitro, do what Scar0 has done to improve his performance, and I'm sure you will be happy with the results.

 

[steviep187]

I have a 3.7 and have no issues getting up to speed.
But I also have a CAI, free-flowing exhaust, and a 4.7 Throttle body. To my disadvantage I have a lift and over sized tires...

To get you started however, Disconnect the Neg(-) battery cable for 10 minutes. This will set the computers in "learn" mode.
Then after you reconnect the battery, drive it like you stole it for a while.
Oh and if it has not been done lately change the spark plugs. Do not use Platinum or Iridium plugs in the 3.7! Use only ZFR6F-11G plugs, NGK is OEM brand and what I use. Must be changed every 30K miles.

Mine has the factory optional 245/50/20 tires. I might look into the mods you listed. It just seems choked all the time. The shift points suck also. I have to click it onto "tow/haul mode" just to keep it from downshifting going up gradual hills. My other car is an LS Camaro, so it kind of has me spoiled in the torque department.